This invention relates to a process for preparing a coal or lignite fuel, which contains sulfur, for combustion. In another aspect, this invention relates to a process for preparing coal or lignite, which contains sulfur, for combustion wherein the amounts of sulfur containing air contaminants normally emitted from such combustion are materially reduced. In another aspect, this invention relates to a method for preparing coal or lignite, which contains sulfur, for combustion with reduced emissions of contaminants whereby the prepared fuel can be shipped, stored and used in conventional equipment. In still another aspect, this invention relates to a method for burning coal or lignite, which contains sulfur, with reduced emissions of sulfur containing air contaminants wherein the coal or lignite is admixed with an inorganic material prior to burning the coal or lignite.
For many years, there has been a shift toward the use of petroleum materials, such as oil and natural gas, for satisfying our energy needs by burning such materials. Because of recent economic and political developments, there has been a drastic increase in the cost of energy sources, such as oil and natural gas. In view of the increased prices for oil and natural gas and becuase of real and potential shortages of these materials, various alternative sources of energy have been investigated.
It has long been known that vast resources of coal and lignite are available as alternative sources of energy in this country. Thus, a very simple solution to our increasing energy requirements would be to utilize coal and lignite as an energy source. Recently, many utility companies, industrial facilities and the like, have either partially or totally changed their sources of energy to coal or lignite because of the availability and cost of such alternate energy sources.
Just as interest has shifted to alternative sources for energy, there has been an increased emphasis placed on "clean burning" fuels. The term, "clean burning" is a term that broadly includes the combustion of various fuels without the production of noxious and harmful combustion products such as sulfur oxides and the like. In fact, there has been a rash of rather strict legislative and regulatory restrictions or limits placed on the amount of contaminants such as sulfur oxides that can be emitted into the atmosphere. It is, of course, well known in the art that energy sources such as coal, lignite, oil and the like, that contain sulfur will produce large quantities of sulfur oxide contaminants.
Unfortunately, much of the coal and lignite found in this country in commercial quantities do contain sulfur in varying quantities. When such sulfur containing coal and lignite materials are burned, sulfur oxides are produced and are emitted into the atmosphere, unless very costly and elaborate measures are undertaken to remove the sulfur oxides from the flue gases coming from the combustion equipment.
In an effort to satisfy various legislative and regulatory restrictions on the amount of sulfur oxides that are emitted into the atmosphere by burning sulfur containing coal and lignite, many types of methods and apparatus have been utilized to minimize such emissions. Almost universally, such methods and apparatus have added to the cost of the conversion of the sulfur-containing coal or lignite into useful energy. In fact, in order to meet rigid requirements pertaining to emissions of sulfur oxides, the cost of various methods and apparatus for reducing sulfur oxide emissions such as by use of complicated and costly scrubbers, precipitators and the like, have virtually made some coal and lignite supplies unattractive for the production of needed energy.
In view of the foregoing, it is highly desirable that inexpensive and practical methods be developed for converting sulfur-containing coal and lignite into useful energy with reduced emissions of sulfur containing air contaminants.